Ignition distributor with surface changing contacts



y 1965 F. w. HAR-TMAN, JR 3,182,142

IGNITION DISTRIBUTOR WITH SURFACE CHANGING CONTACTS Filed April 27. 1961 INVENTOR. /Elm flfl /emuM/c Jwear 411 her:

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United States Patent 3,182,142 IGNITION DISTRIBUTOR WITH SURFACE CHANGING CONTACTS Frank W. Hartman, Jr., Oshkosh, Wis, assignor, by mesne assignments, to Kiekhaefer Corporation, Chicago, 111.,

a corporation of Delaware Filed Apr. 27, 1961, Ser. No. 106,029 9 Claims. (Cl. 200-30) This invention relates to a circuit switching means and particularly to a circuit breaker or ignition contactor assembly forming a part of the ignition system of an internal-combustion engine and the like.

The ignition system of an internal-combustion engine includes a pair of points or contacts constituting a switch which is cylically opened and closed to establish a train of ignition pulses. The contacts are sequentially connected to energize the spark plug or the like in the firing chambers. Normally, the one contact is stationarily mounted and the other contact is movably mounted and biased toward a timing cam by a suitable tension spring. The timing cam is coupled to the movable contact and driven by the engine to establish proper timing of the electrical ignition pulses.

The alignment and the surface condition of the contacts greatly afiects the proper operation for opening or closing of the contacts. The spark formed between the contacts tends to concentrate at aligned points or areas of lowest resistance. The concentrated spark results in the formation of non-conducting oxides on the surface and the transfer of metal from one surface to the other. The non-conducting oxide surface results in malfunctioning during starting and the transfer of metal results in a peak and crater configuration which lowers the effective rate of contact opening and the firing voltage developed in the circuit.

The lubricant employed in rotating parts associated with the conventional ignition contactor assembly may flow between the contact points and further lower the contact resistance and increase the contact erosion.

The high speed opening and closing of the contacts results in vibration and rebounding upon closing of the contacts. The contacts then exhibit a high resistance immediately prior to complete breaking or opening of the contacts and may cause the engine to misfire because of a reduction in the power generated in the firing circuit. The rebounding of the contacts is directly related to the resonant vibration of the contact assembly. Resonant vibration is dependent upon the mass of the contacts and the supporting bracket as well as the breaker tension spring biasing the movable contacts against or toward the cam.

In accordance with the present invention, relative movement is provided between a large floating contact means and relatively small opposed contact means. Consequently, a relatively cool surface is continuously presented to the small contact means and repetitive arcing at a given point is eliminated with any metal transfer due to arcing distributed over the large disc. The detrimental cone and crater formation of presently known assemblies is consequently avoided.

In accordance with another aspect of the present invention, the contacts are spaced from the driving cam with an actuating sliding member operatively coupling The sliding member is held in a relatively large rigid mounting block which is also adapted to carry the stationary contacts. The movable contact is rotatably carried by a resilient biasing means 3,182,142 Patented May 4, 1965 in alignment and engagement with the outer end of the sliding bar. Rotation of the cam then causes the floating contact to move into and out of engagement with the stationary contacts.

The sliding bar maintains the contacts in spaced relation to the lubricants to prevent contamination of the contacts. More important, the assembly establishes a high resonant vibration frequency becauseof the rigidity and support of the assembly and the straight line actuation of the contacts. Effects of inertia with respect to the contact point mechanism is therefore substantially reduced and greatly improves the operation of the contact assembly particularly at high speeds.

The drawing furnished herewith illustrates the best mode presently contemplated for carrying out the invention.

In the drawing:

FIG. 1 is a top plan view of an ignition contactor assembly for an internal-combustion engine constructed in accordance with the present invention;

FIG. 2 is a perspective view, with parts broken away, of the contactor illustrated in FIG. 1;

FIG. 3 is a fragmentary horizontal section through the contact assembly shown in FIGS. 1 and 2; and

FIG. 4 is a view similar to FIG. 1 illustrating a second embodiment of the invention.

Referring to the drawing and particularly to FIGS. 1 and 2, the illustrated embodiment of the invention includes a cam 1 secured to the terminal end of a shaft 2. The cam 1 is formed with a generally elliptical cross section establishing diametrically opposite contact opening lobes or portions 3. A pair of stationary contacts 4 and a relatively movable contact 5 are carried by a mounting plate 6 which is secured adjacent to the cam 1. An actuating bar 7 is slidably mounted upon plate 6 and couples the cam 1 to the movable contact 5 for cyclically opening and closing of contacts 4 and 5.

Shaft 2 is driven in synchronism with an internal-combustion engine, such as a two-cycle outboard motor of which only the top flywheel portion is illustrated, and in which the contacts 4 and 5 are connected as a switch means for establishing firing pulses to the firing chamber or chambers of the engine, not shown.

The mounting plate 6 is carried by a relatively fixed breaker plate 8 of the motor. A pivot screw 9 secures one end of the mounting plate 6 to the breaker plate 8. An adjustment screw 10 passes through a slot 11 in the plate 6 and threads into a suitably tapped aperture in plate 3 to allow releasably locking of the plate 6 and therefore contact 4 with respect to the cam 1. By suitable adjustment of the mounting plate 6, a desired gap between the contacts 4 and 5 is established as more fully described hereinafter.

The movable contact 5 is a relatively large disc-like member which is rotatably mounted upon plate 6 in spaced relation to cam 1 in the following manner.

A tab 12 is bent upwardly from the plate 6 along the edge generally diametrically opposite from the location of the cam 1 with the plate 6 properly attached to the breaker plate 8. A split annular spring 13 of suitable spring steel is secured at the split ends to the tab 12 by suitable rivets 14. The spring 13 is disposed to present a movableportion toward the cam 1. An insulating disc 15 is mounted upon the movable portion of the spring 13 generally in alignment with the tab 12 and the cam 1 and includes a central boss 16 which projects rearwardly through a suitable opening in spring 13. A supporting shaft 17 is rotatably journaled within the boss 16 and secured to the spring 13 by a hex nut 18 which is threaded onto the end of the shaft 17. A hearing washer 19 and an insulating washer 2d are disposed between the hex nut 13 and the spring 13 and with the boss 16 of disc 15 electrically insulate the rotating shaft 17 from the spring.

The movable contact is centrally apertured as at 21 and secured as by a press fit or the like upon the shaft 17 to rotatably support the contact 5 for free floating move ment about the axis of the shaft and to establish axial movement of the contact 5 in response to themovernent of the surface of cam l.

The illustrated bar 7 is generally a plate-like member which is slidably mounted in a vertical plane. The bar includes a rounded bearing end 22 which engages the cam I to provide a low friction sliding contact. The opposite end of the plate-like bar 7 is formed with a flat contact engaging face 23 which bears upon the disc contact 5.

The plate-like bar 7 is slidably supported with an actuating bar retaining assembly 24. The assembly 24 includes a block-like base 25 of suitable insulating material secured to plate 6. Base 25 includes a U-shaped recess 26 generally conforming to the cross section of bar 7 and the recess 26-is aligned with the axis of the cam 1 and the axis of the contact 5. A cover 27 is secured overlying the recess 26 by a plurality of bolts 28 to slidably hold bar 7 for reciprocal movement within recess 26'. The bolts 28 project downwardly through the cover 27 and the block-like base 25 andthread into suitably'threaded apertures 29' in the mounting plate 6 to rigidly interconnect the various parts and to properly align the actuating bar with the cam ii and the contact 5.

As the cam 11 rotates, the bar 7 is forced to reciprocate within the recess in response to the positive force applied by the lobes Softhe cam 1 and the return force applied by the spring 13' through the insulating disc and the contact 5. The contact 5 which is carried by the spring 13'is therefore moved into and out of engagement with the contacts 4 The pair of contacts 4 are small disc-like members secured to the block-like base on opposite sides of the actuating bar 7. The contact 4, shown to the left in FIG. 1, is mounted on the base 25 by an S-shaped connector 3i) which is secured to the corresponding side of the base 25 by a small mounting bolt 31. A contact carrying arm 32 of connector 3t? extends inwardly adjacent the disc contact 5 to properly locate the contact din alignment with the outer peripheral portion of the contact 5. A terminal arm 33 of connector 39 projects outwardly from base 25 at the opposite end of the connector 39 and is apertured' to receive a connecting lead, not shown, for connection to the ignition coil, not shown.

'The opposite contact 4, shown to the right in FIG. 1, is similarly mounted on base 25 by an L-shaped connector 34 which is secured to the opposite side thereof by a small bolt 35. Connector 34 is suitably grounded to. complete the ignition circuit. The current path is thus from the one contact 4, through disc 5 andto the other contact 4 and thus provides, in effect, a pair of circuit breakersconnected in series.

The operation of the illustrated embodiment of the invention is summarized as follows. I

The contacts and cooperating supporting assembly are securedto the mounting plate 6 which in turn is secured to the breaker plate 8. Prior to tightening of the "adjustment screws 10 the plate 6 is pivoted about the pivot fluence of the cam 31 and the spring 13. The expansion and contraction of thespring 13 moves the contact 5 into and out of engagement with the pair of contacts 4 to stantially eliminated.

screw 9 to establish the desired gap between the contact 5 and the pair of contacts 4.

When the engine is operated, the cam 1 is pistons in the engine.

cam. 1 by the spring'13. The bar 7 therefore reciprocontinuously V rotated in timed relation to the rotation of the various Consequently, the lobes 3 of the a cam 1 continuously move into and out of engagement with V the actuating bar 7 which is held in engagement with the Thestraight line action of the contact 5 in combination with the increased rigidity of the mounting increases the resonant vibration frequency of the assembly and eliminates the inertia effect on the contacts 4 and 5. Rebounding of the contacts 4 and 5 when the contacts close is minimized.

The large disc contact 5 is free to rotate about the axis of the shaft 17 which is coincident with the axis of the disc 5 in the illustrated embodiment of the invention; Therefore, the contact surface of the contact 5 is continuously relocated and a relatively cool contact surface is continuously presented to the contacts 4. This prevents formation of the non-conducting oxide coatings and the creation of objectionable cones and craters. Therefore the contact gap is maintained constant and the firing voltage is held at the maximum or optimum level.

The reduced rebounding of the contacts on closing minimizes the formation of a high. resistance immediately before opening of the contacts. Consequently, the current in the circuit'rapidly rises to provide optimum firing power.

FIG. 4 illustrates an embodiment generally similar to the embodiments of FIGS. 1-3. block-like member 36 replaces the spring 13 and insulating-disc 15 of FIG. 1'. A mounting nut 37 is shown em:- bedded within the resilient block-like member 36 to accept the supporting shaft 17 and rotatably support the con:- tact 5. The resilient block member 36 is mounted'in compression under the action of the actuating bar 7:.

The embodiment of FIG. 4 functions basically in the same manner as that. previously described. However, the block member 36 facilitates centering. and actuation of the contacts 4; and 5.

The present invention provides long-life ignition points or contacts for an ignition system and the like by continuously presenting a different contact surface of at least one contact to the opposite contact and thereby preventparticularly pointing out and distinctly claiming the subject matter whichis regarded as the invention.

I claim: a

1. A contact breaker carried on a vibrating support and actuated'to periodically open and close an ignition circuit for an internal combustion engine, comprising a disc-like contact mounted for free rotation about an axis perpendicular to the plane of the contact, a plurality of equicircumferentially distributed contacts of substan-@ tially smaller size'tha'n said disc-like contact and fixedly mounted about therotational axis of" the disc-like contact in facing relation to said disc-like contact and adapted to be connected in the circuit with the disc-like contact establishingconductivity therebetween, and cyclical drive? 'means driven by the engine to rapidl'y and cyclically f axially move the disc-like contact to engage and disengage :the facing contact surfaces at a rate to produce firing-pulses in the ignition circuit. 7

In FIG. 4, a resilient 2. A contact breaker carried on a vibrating support and actuated to periodically open and close an ignition circuit for an internal combustion engine, comprising a disc-like contact, a bearing mount attached to the disclike contact for rotation about the axis of the contact, a drive means rotatable in timed relation to the engine and intermittently operatively coupled to the contact to intermittently move the rotatable disc-like contact axially and at a speed related to the firing sequence of the ignition circuit, and a plurality of fixed contacts of substantially smaller size than said disc-like contact and fixedly mounted in facing relation to said disc-like contact for intermittent engagement of the facing contact surfaces and adapted to be connected in the circuit with the disc-like contact establishing conductivity therebetween, said fixed contacts being arranged to maintain balanced axial forces on the disc-like contact.

3. A contact breaker carried on a vibrating support and actuated to periodically open and close an ignition circuit for an internal combustion engine, comprising a disc contact of an electrically conducting material, a resilient mounting means, a bearing having a fixed member secured to the resilient mounting means and a rotatable member carried by the fixed member and secured to the disc contact to rotatably support the contact for rotation about its axis, coupling means opposite the resilient mounting means in sliding engagement with the contact face of the disc contact, means driven at a speed related to the firing sequence of the circuit for the engine to rapidly axially move the disc contact, and a pair of contacts of substantially smaller size than said disc-like contact and fixedly mounted in facing relation to said disc contact and on opposite sides of the coupling means to engage and disengage the facing contact surfaces and adapted to be connected in the circuit with the disc-like contact establishing conductivity therebetween.

4. In an ignition system for an internal-combustion engine having a timing cam adapted to actuate a timing circuit, a mounting plate adapted to be secured to the engine adjacent said cam, a resilient means secured to the mounting plate and arranged in spaced aligned relation to the cam, a disc-like contact, means to rotatably mount the disc-like contact upon the resilient means, an actuating bar mounted with one end centrally engaging the contact disc and the opposite end engaging the cam when the mounting plate is secured in place, an insulating retaining block secured to the mounting plate between the disclike contact and the cam and having a recess slidably re ceiving the actuating bar, and a plurality of relatively small disc-like contacts carried by the retaining block and arranged in facing relation to the first-named disclike contact on opposite sides of the actuating bar, said contacts being adapted to be connected in said timing circuit.

5. In an ignition system for an internal-combustion engine having a timing cam adapted to actuate a timing circuit, a mounting plate adapted to be secured to the engine adjacent said cam, a resilient means secured to the mounting plate and arranged for spaced aligned relation to the cam, a disc-like contact, means to rotatably mount the disc-like contact upon the resilient means, an actuating plate member mounted with one end diametrically engaging the contact disc and the opposite end engaging the cam when the mounting plate is secured in place, a heavy and rigid insulating retaining block secured to the mounting plate between the disc-like contact and the cam and having a recess slidably receiving the actuating bar, and at least one pair of relatively small disclike contacts carried by the retaining block one each on opposite sides of the actuating plate member and arranged in facing relation to the first-named disc-like contact, said contacts being adapted to be connected in said timing circuit.

6. In an ignition system for an internal-combustion engine having a timing cam adapted to actuate a timing circuit, a mounting plate adapted to be secured to the engine adjacent said cam, a generally annular shaped flat spring having one portion rigidly secured to the mounting plate and an opposite flexing portion arranged for flexing movement in line with the cam, a disc-like contact, means to rotatably secure the disc-like contact upon the flexing portion of the flat spring, an actuating platelike bar mounted with one end diametrically engaging the contact disc and the opposite end engaging the cam when the mounting plate is secured in place to stress the flat spring, an insulating retaining block secured to the mounting plate between the disc-like contact and the cam and having a complementing recess slidably receiving the actuating bar, and at least one pair of relatively small disc-like contacts carried by the retaining block one each on opposite sides of the bar and arranged in facing relation to the disc-like contact, said contacts being adapted to be connected in said timing circuit.

7. In an ignition system for an internal-combustion engine having a timing cam adapted to actuate a timing circuit, a mounting plate adapted to be secured to the engine adjacent said cam, a generally annular shaped flat spring having one portion rigidly secured to the mounting plate and an opposite flexing portion arranged for flexing movement in line with the cam, a disc-like contact, an insulating disc generally corresponding to the disc-like contact and secured to the flexing portion of the spring, bearing means to rotatably secure the disc-like contact to the insulating disc, an actuating plate-like bar mounted with one end diametrically engaging the contact disc and the opposite end engaging the cam when the mounting plate is secured in place to stress the flat spring, an insulating retaining block secured to the mounting plate between the disc-like contact and the cam and having a complementing recess slidably receiving the actuating bar, and at least one pair of relatively small disc-like contacts carried by the retaining block one each on opposite sides of the bar and arranged in facing relation to the disc-like con tact, said contacts being adapted to be connected in said timing circuit.

8. In an ignition system for an internal-combustion engine having a timing cam adapted to actuate a timing circuit, a mounting plate adapted to be secured to the engine adjacent said cam, a compressible block of resilient material secured at one end to the mounting plate and arranged in spaced aligned relation to the cam, a disclike contact, means to rotatably mount the disc-like contact upon the movable end of the block, an actuating bar mounted with one end centrally engaging the contact disc and the opposite end engaging the cam when the mounting plate is secured in place, an insulating retaining block secured to the mounting plate between the disc-like contact and the cam and having a recess slidably receiving the actuating bar, and a plurality of relatively small disclike contacts carried by the retaining block and arranged in facing relation to the first-named disc-like contact on opposite sides of the actuating bar, said contacts being adapted to be connected in said timing circuit.

9. In an ignition contact unit for the ignition circuit in an internal-combustion engine, a pair of contacts mounted in spaced relation with plane contact faces arranged in a common plane and for connection in series in the ignition circuit, a floating contact having a contact face substantially larger than the faces of said pair of contacts and arranged in opposed parallel relation to both of the pair of contacts, means to mount said floating contact for movement relative to said pair of contacts, and means actuated in timed relation to the speed of the internal combustion engine to periodically effect engagement and disengagement between the pair of contacts and the floating contact to correspondingly complete and break the circuit between the pair of contacts at a rate to produce firing pulses in the ignition circuit.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Williams 200-166 Chermendy 200-30 Ives et a1. 200-166 Mack 200-30 Huber 200-30 Molyneux et a1. 200-166 Rainey 200-30 10 Delorme 200-30 Watkins 200-31 Russell 200-30 Dufling 200-30 Baker 200-31 Baker 200-30 Russell 200-30 Smith 200-30 X Jensen 200-19 FOREIGN PATENTS Germany.

BERNARD A. GILHEANY, Primary Examiner.

MAX L. LEVY, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION atent No. 3,182,142 May 4, 1965 Frank W. Hartman, Jr.

It is hereby certified that error appears in the above numbered patant reqiiring correction and that the said Letters Patent should read as :orreeted below Column 3, after line 11, insert the following paragraph:

The spring 13 continuously urges the movable contact 5 and the actuating bar 7 toward the cam l The actuating bar 7 is slidably mounted between the cam l and the contact 5 and is of a sufficient length to maintain the spring 13 partially compressed for all positions of the cam l Signed and sealed this 20th day of October 1965.

JEST W. SWIDER EDWARD J BRENNER sting Officer Commissioner of Patents 

1. A CONTACT BREAKER CARRIED ON A VIBRATING SUPPORT AND ACTUATED TO PERIODICALLY OPEN AND CLOSE AN IGNITION CIRCUIT FOR AN INTERNAL COMBUSTION ENGINE, COMPRISING A DISC-LIKE CONTACT MOUNTED FOR FREE ROTATION ABOUT AN AXIS PERPENDICULAR TO THE PLANE OF THE CONTACT, A PLURALITY OF EQUICIRCUMFERENTIALLY DISTRIBUTED CONTACTS OF SUBSTANTIALLY SMALLER SIZE THAN SAID DISC-LIKE CONTACT AND FIXEDLY MOUNTED ABOUT THE ROTATIONAL AXIS OF THE DISC-LIKE CONTACT IN FACING RELATION TO SAID DISC-LIKE CONTACT AND ADAPTED TO BE CONNECTED IN THE CIRCUIT WITH THE DISC-LIKE CONTACTT ESTABLISHING CONDUCTIVITY THEREBETWEEN, AND CYCLICAL DRIVE MEANS DRIVEN BY THE ENGINE TO RAPIDLY AND CYCLICALLY AXIALLY MOVE THE DISC-LIKE CONTACT TO ENGAGE AND DISENGAGE THE FACING CONTACT SURFACES AT A RATE TO PRODUCE FIRING PULSES IN THE IGNITION CIRCUIT. 